A newly freed con man (David Morse, right, the most compelling reason to see the show) reunites with his embittered son (Christopher Denham). Photo: Joan Marcus

David Morse may not be a household name, but he’s always a pleasure to watch. With his deceptively kind face and low-boil intensity, the silver-haired character actor has enlivened a wide variety of parts, from a puppyish intern on TV’s “St. Elsewhere” to a dogged detective on “House” and a charming pedophile in Paula Vogel’s play “How I Learned To Drive.”

So it’s nice to report that he’s as captivating as ever in the title role of Steven Levenson’s new drama, “The Unavoidable Disappearance of Tom Durnin.”

If only the show, which opened last night at the Roundabout, matched that performance.

When we start, Morse’s Tom is just out of jail, where he did five years for real-estate fraud. He’s trying to pick up where he left off, but everybody rejects him — his scam ruined many people, including his own family.

Tom first reaches out to his son, James (Christopher Denham), whose grungy basement he moves into, temporarily. Forced by the family’s faltering fortunes to drop out of Yale, James now sells medical supplies. He’s also taking a writing class at a community college, where he works on a novella about a Ukrainian road trip on a stolen cement mixer.

The fictions James makes up about his own life are more convincing. When he becomes involved with another writing student, the equally down-on-her-luck Katie (Sarah Goldberg), James tells her, among other fibs, that his father is dead.

James is so socially inept that his idea of flirty small talk devolves into, “I really hate global warming. And pollution. Those are two things that I just . . . I hate them. A lot.” But Denham pushes that stiffness to an extreme, making the young man a blank, expressionless robot it’s impossible to care for.

Tom, on the other hand, is ruthless, cunning and seductive — you can see why people trusted him with their investments. Determined to see his ex-wife, Karen (Lisa Emery), he manages to pry her new address from his son-in-law and former colleague, Chris (Rich Sommer, Harry Crane on “Mad Men”). He even presses Chris into putting in a good word for him at their law firm.

We never do see Tom’s daughter, Annie, Chris’ wife. A pity: She sounds like an interesting woman, far more so than the increasingly grating Katie.

Levenson touches on fascinating issues, like how a family survives an ordeal, but he doesn’t go deep. Only when Morse is onstage — conniving, pleading, lashing out — do we get a sense of what could have been.